According to Car and Driver's Jens Meiners, Cadillac is poised to get a new full-size, rear-wheel drive sedan to slot in above the forthcoming XTS - a model that itself will sit above the CTS when it bows to serve as a combined replacement for the STS and DTS.

To hear C/D's moles tell it, the flagship sedan is still in the early planning stages, but the model is being built at the directive of none other than GM CEO Ed Whitacre. If the rumor is accurate, the forthcoming model is apparently likely to be derived from a stretched Sigma platform, the same architecture that underpins the CTS family. Meiners dismisses thoughts that the car could be built on the much-used Zeta platform that underpins the Chevrolet Camaro, suggesting that it's too heavy and old to support such a vehicle.

With word that a Lambda-based three-row crossover and the BMW 3-Series fighting ATS are on the way for General Motors' Wreath and Crest division, it's becoming increasingly clear that the boys down at The Tubes have hit the product accelerator pedal for their luxury brand. We just hope that this mystery offering means that Cadillac is finally going to cook up something that looks like 2003's showstopping Sixteen concept (above), albeit likely in a scaled-down format.